The first and last flight of the Semroc Hawk

About 2 months ago I built a Semroc Hawk. It came out fairly well as my first glider. It flew decently via hand launch - it had a nice large, lazy circle likely due to my building skills (which is good because I didn't want a straight glide off into the sunset). I put a very light coat of red airbrush paint on the bottom and a light coat of black on the top.

I never had a motor or a location to fly it so it just sat on my bench. Waiting.

Last week I finally got a pack of B6-2 from my LHS.

Today I met up with my friend Jeff to do up some RC lessons on my glider. I brought the Hawk along with some launch equipment to give it a whirl. The winds were variable - going from pretty light to a good huff once in a while. The trick today is that where the RC field is the winds were variable in direction and speed. During my flying lesson the winds were not too bad other than some unexpected pushing around.

After my first training round we got to talking about the rocket stuff and I said "hey i have a rocket we can fly - let's give it a shot". I set it up the pad and got ready to launch. The winds on the ground were pretty light. I push the button and up the glider went, much higher than either of us expected! I'd say it was a good 300 feet up and it was gliding very nicely in a good circle. Unfortunately, the winds up at 300 feet or so were pretty strong. We watched it for a good minute or two minute circling until it finally went behind some trees into the woods. Normally I'd go walking for it but given that we're into hunting season I decided it was not worth it! So glider lost BUT validation that I know what I'm doing to build one is a success! It was a really nice flight and had it been calm recovery would have been great. So back to the drawing board!

I am working on a Semroc Swift for a shot at a pop-pod glider right now. More to come on the glider adventures......

Really? *Every* time we flew ours, the motor ejection shattered the spine of the thing...

PhlAsh said:

Really? *Every* time we flew ours, the motor ejection shattered the spine of the thing...

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Really, Really. It was a great flight! The motor was pretty loose in the tube which likely helped. I'll build up another one and hope that i get the same level of success (but maybe I'll try an A motor).

PhlAsh said:

Really? *Every* time we flew ours, the motor ejection shattered the spine of the thing...

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Mine broke at ejection too!

PhlAsh said:

Really? *Every* time we flew ours, the motor ejection shattered the spine of the thing...

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I think there is a fix for that. I believe part of the issue with the breakage is the one sided vent hole. The sudden asymmetric lateral thrust breaks the spine. I put two vent holes in, one right and one left, and never had the problem again.

Congrats on your "validation". Wait til you start losing helicopters!

Anybody ever successfully upscale the Hawk?

Mine didn't have a vent hole. I know I got it when it first came out so I don't know if that was a change. I haven't had any issue with the spine breaking on the Hawk.

This rocket is very similar to the Estes Astron Falcon of which I have built almost a dozen over the years. All of them, except 1, I have lost to a fly away. The one exception blew apart with one of the infamous "shotgun" ejection changes.

PhlAsh said:

Really? *Every* time we flew ours, the motor ejection shattered the spine of the thing...

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My micromaxx down scale suffered the same failure.

jsargevt said:

Last week I finally got a pack of B6-2 from my LHS.

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½A6-2 is a better motor for general flying of the Estes Falcon (K-13)/AMROCS or Semroc Hawk. In fact, the original Estes instructions recommend the ¼A and ½A 18mm motors for general flying. If you use B motors, the B4-2 would be better than the B6-2. I saw a Hawk glide out of sight on an A8-3. The weather was a bit windy, and the glider was trimmed to glide straight. The field is a square mile sod farm.

After my first training round we got to talking about the rocket stuff and I said "hey i have a rocket we can fly - let's give it a shot". I set it up the pad and got ready to launch. The winds on the ground were pretty light. I push the button and up the glider went, much higher than either of us expected! I'd say it was a good 300 feet up and it was gliding very nicely in a good circle. Unfortunately, the winds up at 300 feet or so were pretty strong. We watched it for a good minute or two minute circling until it finally went behind some trees into the woods. Normally I'd go walking for it but given that we're into hunting season I decided it was not worth it! So glider lost BUT validation that I know what I'm doing to build one is a success! It was a really nice flight and had it been calm recovery would have been great. So back to the drawing board!

I am working on a Semroc Swift for a shot at a pop-pod glider right now. More to come on the glider adventures......

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I would also use the smaller motors to test the Swift. I have seen one take over 2 minutes to land after a B4-2 flight.

mwtoelle said:

½A6-2 is a better motor for general flying of the Estes Falcon (K-13)/AMROCS or Semroc Hawk. In fact, the original Estes instructions recommend the ¼A and ½A 18mm motors for general flying. If you use B motors, the B4-2 would be better than the B6-2. I saw a Hawk glide out of sight on an A8-3. The weather was a bit windy, and the glider was trimmed to glide straight. The field is a square mile sod farm.


I would also use the smaller motors to test the Swift. I have seen one take over 2 minutes to land after a B4-2 flight.

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The B6-2 was chosen due to the limitations on what I could source locally for motors.
I had planned on using 1/2a to mess around with the swift. That one took a little more time but came out pretty nicely. It glides well with a nail in the nose - now i just need to get a few motors and hope for some low-wind days to give it a shot.

I had a hawk. Still do, barely. Flew really well while hand trimming, but broke on the landing on the last, balanced throw. Re balanced it, and it flew remarkably well on an a83, I think it was. Second flight blew the nose cone and it broke again when it contacted ground (1/2 way down the fuselage). I fixed it again, but the last flight broke it in 3 upon landing. What a fragile bird! Anyway, I'm not fixing it again. Gotta try something a little tougher.

I've managed to get four great flights out of mine without any damage so far (knocking on wood). Have flown it twice on 1/2A6-2's and twice on A8-3's. I've built a mount so the next time out I'm gonna try a 13mm motor (not sure which yet) to see how that works out.

Mine snapped at ejection, despite having two vent holes, on its first flight. I just repaired it last night by lightly epoxying two lengths of .04" diameter carbon fiber rod down the spine. It still glides well when tossed, so it will get another attempt at the next calmish launch. Given the extra weight I'm not too optomistic though. Repairing it was really an excuse to experiemnt with the carbon fiber rod more than anything.

I finished up my build of a Semroc Hawk this evening. I'd still like to reinforce some joints with fillets and do some sanding, but it's gliding well as it is right now. I'm curious to hear from others that have had structural success on multiple flights....how much did you reinforce the Hawk versus keeping it light?

Gonna go George Romero here with "Night of the Living Thread."

Just ordered a Semroc Hawk on eBay for $15 after shipping. I should have it Monday afternoon, ready for me to start building it New Year's Eve. I've got West Systems G/Flex epoxy, as well as some Rocketpoxy. Any suggestions from experienced Hawk builders?

Use wood glue. Epoxy is heavy and overkill.

John Kemker said:

Gonna go George Romero here with "Night of the Living Thread."

Just ordered a Semroc Hawk on eBay for $15 after shipping. I should have it Monday afternoon, ready for me to start building it New Year's Eve. I've got West Systems G/Flex epoxy, as well as some Rocketpoxy. Any suggestions from experienced Hawk builders?

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i would recommend staying away from epoxy on these small gliders. Wood glue, used sparingly, is more than adequate. Weight is the enemy of the glider.

Take your time and make sure everything is lined up nice and straight. The instructions were clear and yield a nice flying device.

Good luck’

jsargevt said:

i would recommend staying away from epoxy on these small gliders. Wood glue, used sparingly, is more than adequate. Weight is the enemy of the glider.

Take your time and make sure everything is lined up nice and straight. The instructions were clear and yield a nice flying device.

Good luck’

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How about Medium CA instead of wood glue?

BABAR said:

Congrats on your "validation". Wait til you start losing helicopters!

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Dad had flown real helicopters for Army back in Nam. I had flown cessnas as teen. Well I got a nice $400 R/C heli once with tail rotor and variable pitch blades, not one of those wussy easy to fly coaxials. It flew nothing like flight sim helicopter. It went up skids just left ground then pitched nose forward and right rapidly. I was being very careful to ease throttle up slowly. Didn’t even have time to mutter oops or oh sh*t. I saw blades munch the floor. Blade splinters went flying past us both. Dad mumbled something technical I can’t recall but he knew the behavior that happened.

I had extensive time on Alphajet 64mm EDF plane and thought I could handle a heli. I couldn’t. I promptly rage quit R/C heli hobby. Dad’s helicopter pilot buddies laughed and shared pics of R/C heli they destroy too and said real one easier to fly.

Best part about heli hobby... Once rotor tip taps ground at high RPM. All mechanical swashplate and linkage complex crapola gets totaled. Man might as well just burn $$$$$$$.

Stick with rockets... What was that song turn the page? Yeah that’s what I did about heli hobby.

Andrew_ASC said:

Dad had flown real helicopters for Army back in Nam. I had flown cessnas as teen. Well I got a nice $400 R/C heli once with tail rotor and variable pitch blades, not one of those wussy easy to fly coaxials. It flew nothing like flight sim helicopter. It went up skids just left ground then pitched nose forward and right rapidly. I was being very careful to ease throttle up slowly. Didn’t even have time to mutter oops or oh sh*t. I saw blades munch the floor. Blade splinters went flying past us both. Dad mumbled something technical I can’t recall but he knew the behavior that happened.

I had extensive time on Alphajet 64mm EDF plane and thought I could handle a heli. I couldn’t. I promptly rage quit R/C heli hobby. Dad’s helicopter pilot buddies laughed and shared pics of R/C heli they destroy too and said real one easier to fly.

Best part about heli hobby... Once rotor tip taps ground at high RPM. All mechanical swashplate and linkage complex crapola gets totaled. Man might as well just burn $$$$$$$.

Stick with rockets... What was that song turn the page? Yeah that’s what I did about heli hobby.

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Cool story. Actually I was referring to losing helicopter recovery rockets!

I inherited a Hawk kit from another club member and am building it right now. I'm going to heed the warning about the force of the ejection charge shattering the fuse and will be adding vent holes opposite each other on the motor pod.

I'm curious to see how it performs, as I've read that they tend to lawn dart even though they hand trim out perfectly. Read an article where one guy solved the problem by simply adding flaps to either side of the stab to pull the nose up at ejection. I'm not expecting any problems though, as I can't believe any manufacturer would release a model with an inherent defect in design. Guess I'll find out when I maiden it.

Did the Semroc Hawk assembly today. Used Medium CA (despite the silence on the question from folks on here) and with a bit of nose weight trimmed out nicely. Looking for some big Sharpies to "paint" it with, as the consensus seems to be stay away from actual paint, as it's too heavy.

My planned solution to the "shotgun ejection" system is to 1) Sand the centering rings a bit until they slide freely and 2) lubricate the motor assembly with talcum powder (not cornstarch). I'll have to be careful to not sand or talc too much, otherwise the motor mount might fall out on the pad!

John Kemker said:

Did the Semroc Hawk assembly today. Used Medium CA (despite the silence on the question from folks on here) and with a bit of nose weight trimmed out nicely. Looking for some big Sharpies to "paint" it with, as the consensus seems to be stay away from actual paint, as it's too heavy.

My planned solution to the "shotgun ejection" system is to 1) Sand the centering rings a bit until they slide freely and 2) lubricate the motor assembly with talcum powder (not cornstarch). I'll have to be careful to not sand or talc too much, otherwise the motor mount might fall out on the pad!

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Will you be using a 13mm motor then? I built an adapter for mine with a small streamer attached, and will probably use a 1/2A3-2T for its first flight to avoid a long walk or having it thermal away.

Rktman said:

Will you be using a 13mm motor then? I built an adapter for mine with a small streamer attached, and will probably use a 1/2A3-2T for its first flight to avoid a long walk or having it thermal away.

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Yes. It came with the 13mm adapter, streamer included, and I'm going to go with that.

I notice that the eRockets Hawk kit uses a basswood fuselage. That should greatly reduce, if not eliminate, the problem of the fuse snapping from the force of the ejection charge. It also uses tab and slot construction to ensure things get aligned more precisely. My kit was the older one produced by Semroc which doesn't incorporate those improvements.

Rktman said:

I notice that the eRockets Hawk kit uses a basswood fuselage. That should greatly reduce, if not eliminate, the problem of the fuse snapping from the force of the ejection charge. It also uses tab and slot construction to ensure things get aligned more precisely. My kit was the older one produced by Semroc which doesn't incorporate those improvements.

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My Semroc Hawk has a basswood fuselage and tabbed construction.

Maidened my Hawk today on a 1/2A3-2T (small field). Flew great...for the 12 or so seconds it was aloft. At a minimum I'd suggest an A10-3T or A8-3. The 13mm 1/2A only got it up to about 50' or 60'—barely enough time to transition into a glide. BTW the dual vent holes opposite each other suggested in #5 worked great, no issues with the ejection charge (I have the balsa fuselage version).

Rktman said:

I notice that the eRockets Hawk kit uses a basswood fuselage.

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Eric,

Back in the day, Spruce was the material of choice for glider fuselages.

Dave F.